I hopped distros for a while and they were all, well, Linux. Different package manager, different installation process, different default Desktop Environment, etc, but in the end they were all the same to me too.
Until I met Arch.
The big difference for me is: the ArchWiki and the AUR (Arch User Repository).
The ArchWiki is easily the best Linux guide/resource out there. Whatever I need to do, I'll find how to it in there. Of course it's not all Arch-specific, but everything in there is certain to work for Arch users.
And of course, the AUR. Arch is usually regarded as a distro for more advanced users, "harder to install and use than others", everyone says. But, with my experiece with different distros, if there is one thin I can tell you without any doubt is this: I had a much, much easier time with Arch than with any other distro out there. And that is mostly because of the AUR, whatever package I need, it's there. I'm always one command away of having the software I need available and I never need to compile anything.
This is obviously my personal opinion but, between the most awesome package manger in the planet (pacman), the wiki, the AUR, and the Arch Way there is no way one can use Arch and not realize it's the most complete distro out there 